Dr. Huffenpuff wants to manipulate amount of sugar a child consumes to examine whether it affects activity levels. Children participate in the study for four weeks. Half the time, the children are given a high-sugar diet; the other half of the time, the children are not allowed foods with added sugar. (Conditions were counter-balanced). The entire time, children wore activity monitors that measured daily steps. What is the most appropriate claim that can be made based on her study’s design?